Vulnerability Note VU#507496

GIGABYTE BRIX UEFI firmware fails to implement write protection and is not cryptographically signed

Overview

GIGABYTE BRIX UEFI firmware for the GB-BSi7H-6500 and GB-BXi7-5775 platforms, versions vF6 and vF2 respectively, fails to properly set the BIOSWE, BLE, SMM_BWP, and PRx bits to enforce write protection. It also is not cryptographically signed. These issues may permit an attacker to write arbitrary code to the platform firmware, potentially allowing for persistent firmware level rootkits or the creation of a permanent denial of service condition in the platform.

Description

GIGABYTE UEFI firmware for the GB-BSi7H-6500 and GB-BXi7-5775 platforms fails to properly set the BIOSWE, BLE, SMM_BWP, and PRx bits. As a result, the BIOS is not protected from arbitrary write access and may permit modifications to the SPI flash.

GIGABYTE UEFI firmware for the GB-BSi7H-6500 and GB-BXi7-5775 platforms is not cryptographically signed and is served over HTTP from the vendor's support pages without a checksum. An attacker in the position to do so may introduce arbitrary modifications to the firmware that the system has no means to detect.

Note that the affected GIGABYTE firmware is a vulnerable implementation of an AMI reference design that does not, by default, appear to be affected by these issues. For more information about these findings, refer to the Cylance advisories, CLVA-2017-01-001 and CLVA-2017-01-002.

Impact

A local, authenticated attacker may be able to execute arbitrary code with the privileges of system firmware, potentially allowing for persistent firmware level rootkits or the creation of a permanent denial of service condition in the platform.

Solution

The vendor has indicated that firmware version F7 for the GB-BSi7H-6500 will be released in April to address these issues. Users should monitor the product page or contact the vendor for update availability.

The vendor has indicated that the GB-BXi7-5775 is end of life and will not receive new firmware.

The CERT/CC is currently unaware of a practical solution for these problems.